665884592640 has 800 divisors, whose sum is σ = 2549919897360. Its totient is φ = 165495177216.

The previous prime is 665884592591. The next prime is 665884592647. The reversal of 665884592640 is 46295488566.

665884592640 is a `hidden beast` number, since 6 + 6 + 588 + 4 + 5 + 9 + 2 + 6 + 40 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 431365222656 + 234519369984 = 656784^2 + 484272^2 .

It is not an unprimeable number, because it can be changed into a prime (665884592647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 384237214 + ... + 384238946.

Almost surely, 2^665884592640 is an apocalyptic number.

665884592640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665884592640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1274959948680).

665884592640 is an abundant number, since it is smaller than the sum of its proper divisors (1884035304720).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665884592640 is a wasteful number, since it uses less digits than its factorization.

665884592640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1894 (or 1869 counting only the distinct ones).

The product of its (nonzero) digits is 99532800, while the sum is 63.

The spelling of 665884592640 in words is "six hundred sixty-five billion, eight hundred eighty-four million, five hundred ninety-two thousand, six hundred forty".